The company I work for manufactures ATMs. Our machines do NOT run Windows or any other Commercial OS. They are fully compliant with PCI and ADA requirements. They include the headphone jack and audio prompts you mention among other requirements.
So what was the requirement that necessitated the use of Windows ? It's only a platform and is not needed to accomplish those goals. The OS used is irrelevant to ease-of-use by the disabled. The ADA guidelines state that ALL new machines manufactured after a certain date must include those features. Older machines of course are grandfathered in, due to the excessive cost of upgrading or overhauling them. f you take ANY machine out of service to replace it, it must be replaced with a terminal that meets the current guidelines.
You might be surprised to find out there were still terminals through the end of last year using only single DES encryption. At the end of the year we shut down all of the terminals we handle processing for that were not upgraded. I can't say the same for other processors or sponsor banks. It wouldn't surprise me in the least to find out people were still operating those insecure out of compliance terminals.
Funny the ATMs installed in the banks cost around $50k While ours are in the range of $1500.00 - $2000.00. We have manufactured to date around 6000 machines and handle processing for over 12,000 terminals (ours and other manufacturers). to date none of our machines have been subject to fraud via tampering in any fashion. that includes denomination fraud, code insertion, skimming devices.
Quite frankly the process we have to go through for certification of any hardware or software change, I don't understand how the big guys keep ending up so vulnerable. They attempt to freeze, drill, Shock, inject foreign substances, pry apart, cut open, and whatever else they can come up with to assault our terminals to ensure they are not able to be physically or electronically compromised. Do the big guys get an automatic pass on the certification process, just because of who they are ? We sure as heck don't..